The first phase of the study consisted of 3 randomized 5-hour laboratory sessions, each beginning between 3 and 5 PM. Subjects were tested individually, and sessions were conducted in a comfortable room and separated by at least 48 hours. Women were examined regardless of menstrual cycle phase because acute alcohol responses do not vary by menstrual phase.63 To reduce potential alcohol expectancies, participants were told that they might receive a beverage containing alcohol, a stimulant, a sedative, a placebo, or a combination of these substances. Participants were randomized to dose order and tested under double-blind conditions. In each session, they ingested a beverage containing placebo (0.0 g/kg; 1% volume of ethanol as taste mask), a low alcohol dose (0.4 g/kg), or a high alcohol dose (0.8 g/kg). The beverage was administered in clear plastic-lidded cups in 2 equal portions that were each consumed during a 5-minute interval and separated by a 5-minute interim rest. The beverages contained 190-proof ethanol prepared with water, flavored drink mix, and a sucralose-based sugar substitute. The mean total beverage volume was 471 mL (range, 327–668 mL), and doses for women were 85% of those of men to adjust for sex differences in total body water.64,65
